Referring to FIG. 1, a conventional tool cabinet as disclosed in Chinese Patent No. 204868803U includes a cabinet body 1, a working platform unit 2 disposed on the cabinet body 1, two lifting units 3 (only one is shown) respectively disposed at opposite sides of the cabinet body 1 and connected to the working platform unit 2, a linkage unit 4 interconnecting the lifting units 3, and a driving unit 5 disposed on the working platform unit 2. The cabinet body 1 includes two slide rails 101. The working platform unit 2 has two extension members 201 respectively and slidably inserted into the slide rails 101. Each of the lifting units 3 has a guide tube 301, a nut 302 that is disposed on a top end of the guide tube 301, a threaded rod 303 that is rotatably connected to the working platform unit 2 and that is threadedly connected to the nut 302, and a transmission bevel gear 304 that is disposed on a top end of the threaded rod 303. The linkage unit 4 includes a linkage rod 401, and two linkage bevel gears 402 that are respectively connected to opposite ends of the linkage rod 401, and that respectively mesh with the transmission bevel gears 304 of the lifting units 3. The driving unit 5 includes a motor 501, and a drive bevel gear 502 that is connected to the motor 501, and that meshes with the transmission bevel gear 304 of one of the lifting units 3.
When lifting or lowering the working platform unit 2, a user needs to start the motor 501 to drive rotation of the threaded rod 303 of the one of the lifting units 3 via the engagement between the drive bevel gear 502 and the transmission bevel gear 304 of the one of the lifting units 3. During the abovementioned rotation of the threaded rod 303, the transmission bevel gear 304 of the one of the lifting units 3 simultaneously drives rotation of the linkage rod 401 via the engagement between the transmission bevel gear 304 of the one of the lifting units 3 and a corresponding one of the linkage bevel gears 402, thereby driving rotation of the threaded rod 303 of the other one of the lifting units 3 (not shown in FIG. 1) via the engagement between the other one of the linkage bevel gears 402 and the transmission bevel gear 304 of the other one of the lifting units 3 (not shown in FIG. 1). For each of the lifting units 3, since the rotation of the threaded rod 303 results in telescopic movement of the threaded rod 303 relative to the guide tube 301 via the engagement between the threaded rod 303 and the nut 302, the working platform unit 2 can eventually be moved upwardly and downwardly along the slide rails 101.
However, when in use, unlike the threaded rod 303 of the one of the lifting units 3, rotation of the threaded rod 303 of the other one of the lifting units 3 is driven via the linkage unit 4 instead of being directly driven by the driving unit 5, so that a delayed rotation of the threaded rod 303 of the other one of the lifting units 3 may occur (i.e., rotations of the threaded rods 303 of the lifting units 3 are not synchronous with each other), which results in twisting of the linkage rod 401 and unsmooth movement of the working platform unit 2. In addition, the drawback of asynchronous rotation of the threaded rods 303 will be much more apparent if the linkage rod 401 is configured to be longer.
Furthermore, when the working platform unit 2 is arrested when moving downwardly with an object or a user's body part accidentally placed between the working platform unit 2 and a top surface of the cabinet body 1, the continuous operation of the motor 501 which drives the working platform unit 2 to move toward the cabinet body 1 may cause damage to the object or injury to the user's body part, or may even cause breakdown of the driving unit 5.